This application claims priority of German application 10023685.5 filed May 16, 2000 and European application 00119988.4 filed Sep. 14, 2000, both applications are pending.
The invention relates to an exchangeable tool assembly for an endoscopic treatment device, comprising a flexible shaft connected at its distal end to a tool unit and at its proximal end to a coupling element, and further comprising a locking mechanism to releasably hold the tool assembly at the treatment device.
Further, the invention relates to an endoscopic treatment device with an afore-mentioned tool assembly.
A tool assembly and a treatment device of the afore-mentioned kind are known from U.S. Pat. No. 5,349,940.
Such an endoscopic treatment device can be used in technical applications, in the medical field, in particular in the field of minimally invasive surgery, and also in dental medicine or dental techniques.
In technical applications a treatment carried out with the treatment device includes, for example, removing burrs from forged pieces, grinding notches in turbine blades, grinding off corrosion for surface analysis, for example crack testing, grinding off welding seams, boring holes, etc. In minimally invasive surgery such a treatment device can be used to treat tissue in the body through a small incision, for example for excising tissue.
In general such an endoscopic treatment device is intended to be used for universal endoscopic treatments and/or analysis under visual control, mainly with a rotating tool, at difficultly accessible locations.
In known rigid devices, the transmission of motion from the proximally located motor to the distally located working tool is accomplished with a rigid drive shaft or with transmission belts. These transmission belts require gears and deflection rollers, which lead to losses in space and efficiency. The construction of the power transmission from the proximal motor to the distal working unit is complicated and subject to disturbance. Rigid drive shafts lying parallel and close to the longitudinal axis of the working shaft cannot be coupled directly to the motor, because the motor has certain minimal dimensions which obstruct the fixed optic lenses. However, this would not be the case with fiber optics, which, however, has less resolution.
Flywheel forces and imbalances, which can occur in use of the endoscopic treatment device at the tool unit and at the transmission element in form of the flexible shaft lead to vibrations which cause an upper limit to the rotary speed. The lower speeds resulting from this construction lead to a reduction in removal or excising capacity.
Furthermore, it is not only the distally located tool unit which is subject to wear in such a treatment device, but also the flexible shaft and the coupling of the flexible shaft to the motor. Treatment devices are known, where the tool unit and the flexible shaft and the coupling element cannot be exchanged or at least not simply, as it is, for example, the case with the tool assembly known from U.S. Pat. No. 5,349,940, whereby maintenance of such treatment devices is very cost intensive.
Medical devices are known which must be operated with flushing fluid to lubricate the bearings. Such a treatment device is therefore not usable in technical applications. The exchangeable tool assembly contains all of the wearing elements such as bearings, the working head as well as the shaft and shaft protector. However, it is rigid and due to its construction it is not designed for higher rotary speeds.
From the document U.S. Pat. No. 5,349,940 mentioned at the outset an endoscopic treatment device is known, comprising an exchangeable tool assembly, wherein the tool assembly comprises a flexible shaft, which is connected at its distal end to a tool unit and at its proximal end to a coupling element. The tool unit comprising the working head, for example a milling head, is releasably connected to the flexible shaft via a screw and plug coupling so that the coupling between the tool unit and the shaft must be released at first in order to exchange the tool unit. The flexible shaft itself comprises a plurality of parts and exchange and mounting of the shaft to the device is difficult. The connection between the tool unit, the flexible shaft and the motor therefore consists of a plurality of parts, i.e. several single parts must be fitted, plugged and screwed together, whereby the exchange of this known exchangeable tool assembly and, thus, the maintenance of the treatment device is complicated.
It is, therefore, an object of the present invention to improve an exchangeable tool assembly for an endoscopic treatment device mentioned at the outset as well as to provide such a treatment device, such that the tool assembly can be simply and quickly exchanged, wherein all parts subject to wear are exchangeable with low expenditure of handling.
According to the present invention, this object is achieved with an exchangeable tool assembly for an endoscopic treatment device, comprising:
a tool unit;
a coupling element for coupling said tool assembly to a motor of said treatment device;
a flexible shaft having a distal end and a proximal end, said distal end being connected to said tool unit and said proximal end being connected to said coupling element, said flexible shaft transmitting a rotary movement of said motor to said tool unit, said flexible shaft being connected to said tool unit such that said flexible shaft and said tool unit form a jointly exchangeable unit; and
a locking mechanism for releasably holding said tool assembly at said treatment device, said locking mechanism comprising a locking element arranged at said tool unit and a locking member arranged at said treatment device, which is engageable with said locking element to releasably hold said jointly exchangeable unit formed by said tool unit and said flexible shaft, which can be withdrawn as a whole after disengagement of said locking member from said locking element.
Further, according to the present invention, an endoscopic treatment device is provided with an exchangeable tool assembly according to the present invention.
The afore-mentioned connection between the tool unit and the flexible shaft is advantageous as to a simple exchange of the exchangeable tool assembly, because these two elements subject to wear can be exchanged as an integral unit and thus in an easily handable manner, because they have not to be connected to one another for exchange. Furthermore, this configuration advantageously makes it possible to configure the tool unit and the flexible shaft in miniaturized form, whereby very high rotary speeds of the tool assembly are possible, without vibrational dampening measures, such as dynamic balancing, dampening and friction-reducing measures being additionally necessary. Such a miniaturization cannot be envisaged with the exchangeable tool assembly known from U.S. Pat. No. 5,349,940 because of its constitution of multiple parts. According to the present invention, the locking mechanism is configured such that locking of the tool assembly, i.e. the integral unit consisting of the tool unit and the flexible shaft, can be accomplished by means of a locking element arranged at the tool unit, in which a locking member of the treatment device engages. The flexible shaft is then axially immobilized at the treatment device through the locking of the tool unit.
The connection between the flexible shaft and the tool unit can be realized by assembling, for example by soldering or welding, or the tool unit can be connected to the flexible shaft in one piece or in monolithic fashion.
In a preferred embodiment the flexible shaft is connected to the proximal coupling element such that the coupling element can be withdrawn together with the flexible shaft and the tool unit after releasing the locking mechanism.
In this embodiment the tool unit, the flexible shaft as well as the coupling element and thus all parts subject to wear are exchangeable in simply handable manner, and for immobilizing this unit at the treatment device only the afore-mentioned locking mechanism comprising the locking element arranged at the tool unit and the locking member arranged at the treatment device is to be manipulated.
The locking mechanism according to the present invention having a locking member of the treatment device engageable into a locking element of the tool unit represents a quickly releasable and quickly lockable locking mechanism, which essentially simplifies the exchange of the exchangeable tool assembly. As already mentioned all parts subject to wear are integrated in one exchangeable element, whereby handling of the exchange is simplified and furthermore, the costs of the exchangeable tool assembly are reduced with respect to the manufacturing expenditure.
In a further preferred embodiment the tool unit comprises a working head and a tool shaft, and said locking element is configured as an annular groove in that tool shaft.
When the working head and the tool shaft rotate, the locking member engaging in the groove axially secures the exchangeable tool assembly. The advantages of this measure are that a constructively very simple locking mechanism is achieved, which can be realized in a simple production operation, namely by machining the circumferential annular groove at the tool shaft. Such a locking mechanism has the further advantage that locking is achieved with a minimal requirement on additional shaft diameter. By locking the tool assembly in its distal region, namely at the tool unit, a good tool guidance with the flexible shaft is made possible. If the tool assembly were locked proximally at the motor coupling, the tool unit when subjected to axial force would be deflected proximally due to the spring action of the flexible shaft. Thereby, handling of the tool would be rendered inaccurate.
In a further preferred embodiment a bearing bush is provided which receives an axial portion of the tool shaft and has a slot configured such that the locking element can pass through the slot.
This measure has the advantage that the rotating tool and the bearing bush are simultaneously locked by the locking mechanism. The bearing bush can be withdrawn from the treating device when the tool assembly is withdrawn, and can be exchanged as a part subject to wear. As will be described later on the bearing bush has a slight radial play in the treatment device.
In a further preferred embodiment the flexible shaft is configured as a braided cable, or as a profile in form of a wire, tube or angular profile.
These measures represent advantageous configurations of the flexible shaft, in order to impart a certain flexibility thereto. With a flexible shaft, the tool assembly can be also used in such treatment devices, which comprise a flexible working shaft in order to reach difficultly accessible working areas. With a configuration of the flexible shaft as a hollow profile, the shaft can also be used for transportation of material, signals or information to the working head of the tool unit and therefrom.
In a further preferred embodiment the flexible shaft is made from a highly flexible alloy.
Such highly flexible alloys can be Nitinol(copyright) or Tinel(copyright).
In a further preferred embodiment a spiral is provided which rotatably receives an axial portion of the flexible shaft.
With the spiral surrounding the flexible shaft, with a play least possible and not rotating therewith, a stabilizing rigidity can be given to the flexible shaft despite its flexibility, and imbalances cannot build up. Imbalance would lead to disturbing vibrations and to frictional losses on the inner side of the spiral.
In this context it is preferred if a mantle, preferably a plastic mantle is provided surrounding the spiral.
The plastic mantle advantageously serves as a vibration damper. Resonance are eliminated by damping which when combining the vibrations could lead to frictional losses. Furthermore, the plastic mantle advantageously protects the spiral against deformations which could arise in assembly or disassembly. Furthermore, it prevents lubricant loss.
A treatment device according to the present invention comprises a tool assembly according to the present invention according to one or more of the afore-mentioned embodiments.
In this context, it is preferred, when the locking member extends perpendicularly to a longitudinal axis of the device and at its end opposite to the longitudinal axis is attached to a holding part of the locking mechanism running parallel to the longitudinal axis.
Further, it is preferred, if the holding part is configured as a biased bracket urged substantially perpendicularly to the longitudinal axis, so that the locking member is movable perpendicularly to the longitudinal axis.
This configuration of the locking mechanism having the locking member arranged at the holding part configured as an elastically biased bracket has the advantage that locking as well as releasing is very easy to handle, in particular, the locking member automatically disengages from the locking element at the tool unit on release of the locking mechanism.
In this context, it is further preferred if the locking mechanism comprises a sleeve displaceable in axial direction, which is configured to be slideable over the bracket and moves the locking member perpendicularly to the longitudinal axis, so that the locking member engages in the locking element of the tool assembly.
Altogether, the locking mechanism according to the present invention has the advantage that no screws have to be tightened or to be released for exchanging the tool assembly, but only the slide sleeve must be displaced in proximal direction whereby the biased bracket with the locking member arranged thereon automatically resiliently moves aside, whereby the locking member disengages from the locking element, and must be displaced in distal direction for locking, whereby the slide sleeve urges the bracket radially inwardly so that the locking member engages the locking element.
In a further preferred embodiment an insert channel is provided which receives the tool assembly, wherein the tool assembly can be introduced into and removed from the insert channel in axial direction, and wherein the tool assembly is received in the insert channel with radial play.
This play has the advantageous effect that imbalances of the tool unit do not have a strong effect. In the region of the bearing bush this measure has the effect that imbalances do not have a strong effect, but are compensated by a minimal movement of the bearing bush. This self-balancing increases the lifetime, because the vibrations caused by friction are minimized. In the region of the flexible shaft this play also has the advantage that the shaft is slightly moved by the imbalances whereby a self-balancing arises which minimizes the vibrations.
In a further preferred embodiment the treatment device comprises a working shaft, in which the insert channel and parallelly thereto a channel for an endoscope is arranged.
In a further preferred embodiment the working shaft comprises in its distal region a flexible part for deflecting the tool unit with respect to a longitudinal axis portion of a proximal region of the working shaft.
By this measure difficultly accessible working regions can be endoscopically treated or analyzed, and the motor rotation can be transmitted through the bend to the tool unit via the flexible shaft.
Further advantages will be apparent from the following description and the attached drawings.
It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention.
The invention will be explained and described in more detail below with reference to selected exemplifying embodiments in conjunction with the attended drawings.